On-site determination of formaldehyde: A low cost measurement device for museum environments

2008 ◽  
Vol 623 (1) ◽  
pp. 109-116 ◽  
Author(s):  
L.T. Gibson ◽  
W.J. Kerr ◽  
A. Nordon ◽  
J. Reglinski ◽  
C. Robertson ◽  
...  
2021 ◽  
Vol 10 (1) ◽  
pp. 71-81
Author(s):  
Robin Werner ◽  
Jaroslaw Kita ◽  
Michael Gollner ◽  
Florian Linseis ◽  
Ralf Moos

Abstract. A novel measurement device for simultaneous high temperature measurements of the electrical conductivity and the Hall coefficient has been developed. Simulations were used to design a suitable screen-printed planar platinum heating structure that generates temperatures of up to 600 ∘C by Joule heating. Simulations of the temperature distribution have been validated using thermal imaging. With the hardware setup of two permanent magnetic yoke systems with a magnetic flux density of ±760 mT, the electrical conductivity and the charge carrier densities of a silicon wafer and a gold film were measured, as examples of a typical semiconductor with low charge carrier densities but high mobility and a metal representing materials with very high charge carrier densities but moderate mobilities, respectively. Measurements were compared with data from the literature to validate the functionality of the novel, low-cost measurement device.


2020 ◽  
Vol 16 (8) ◽  
pp. 1032-1040
Author(s):  
Laleh Samini ◽  
Maryam Khoubnasabjafari ◽  
Mohamad M. Alimorad ◽  
Vahid Jouyban-Gharamaleki ◽  
Hak-Kim Chan ◽  
...  

Background: Analysis of drug concentrations in biological fluids is required in clinical sciences for various purposes. Among other biological samples, exhaled breath condensate (EBC) is a potential sample for follow up of drug concentrations. Methods: A dispersive liquid-liquid microextraction (DLLME) procedure followed by a validated liquid chromatography method was employed for the determination of budesonide (BDS) in EBC samples collected using a homemade setup. EBC is a non-invasive biological sample with possible applications for monitoring drug concentrations. The proposed analytical method is validated according to the FDA guidelines using EBC-spiked samples. Its applicability is tested on EBC samples collected from healthy volunteers receiving a single puff of BDS. Results: The best DLLME conditions involved the use of methanol (1 mL) as a disperser solvent, chloroform (200 μL) as an extraction solvent, and centrifugation rate of 3500 rpm for 5 minutes. The method was validated over a concentration range of 21-210 μg·L-1 in EBC. Inter- and intra-day precisions were less than 10% where the acceptable levels are less than 20%. The validated method was successfully applied for the determination of BDS in EBC samples. Conclusion: The findings of this study indicate that the developed method can be used for the extraction and quantification of BDS in EBC samples using a low cost method.


2020 ◽  
Vol 16 (4) ◽  
pp. 456-464
Author(s):  
Danilo F. Rodrigues ◽  
Hérida R.N. Salgado

Background: A simple, eco-friendly and low-cost Infrared (IR) method was developed and validated for the analysis of Cefepime Hydrochloride (CEF) in injectable formulation. Different from some other methods, which employ organic solvents in the analyses, this technique does not use these types of solvents, removing large impacts on the environment and risks to operators. Objective: This study aimed at developing and validating a green analytical method using IR spectroscopy for the determination of CEF in pharmaceutical preparations. Methods: The method was validated according to ICH guidelines and the quantification of CEF was performed in the spectral region absorbed at 1815-1745 cm-1 (stretching of the carbonyl group of β- lactam ring). Results: The validated method showed to be linear (r = 0.9999) in the range of 0.2 to 0.6 mg/pellet of potassium bromide, as well as for the parameters of selectivity, precision, accuracy, robustness and Limits of Detection (LOD) and Quantification (LOQ), being able to quantify the CEF in pharmaceutical preparations. The CEF content obtained by the IR method was 103.86%. Conclusion: Thus, the method developed may be an alternative in the quality control of CEF sample in lyophilized powder for injectable solution, as it presented important characteristics in the determination of the pharmaceutical products, with low analysis time and a decrease in the generation of toxic wastes to the environment.


2019 ◽  
Vol 15 (6) ◽  
pp. 628-634
Author(s):  
Rong Liu ◽  
Jie Li ◽  
Tongsheng Zhong ◽  
Liping Long

Background: The unnatural levels of dopamine (DA) result in serious neurological disorders such as Parkinson’s disease. Electrochemical methods which have the obvious advantages of simple operation and low-cost instrumentation were widely used for determination of DA. In order to improve the measurement performance of the electrochemical sensor, molecular imprinting technique and graphene have always been employed to increase the selectivity and sensitivity. Methods: An electrochemical sensor which has specific selectivity to (DA) was proposed based on the combination of a molecular imprinting polymer (MIP) with a graphene (GR) modified gold electrode. The performance and effect of MIP film were investigated by differential pulse voltammetry (DPV) and cyclic voltammetry (CV) in the solution of 5.0 ×10-3 mol/L K3[Fe(CN)6] and K4[Fe(CN)6] with 0.2 mol/L KCl at room temperature. Results: This fabricated sensor has well repeatability and stability, and was used to determine the dopamine of urine. Under the optimized experiment conditions, the current response of the imprinted sensor was linear to the concentration of dopamine in the range of 1.0×10-7 ~ 1.0×10-5 mol/L, the linear equation was I (µA) = 7.9824+2.7210lgc (mol/L) with the detection limit of 3.3×10-8 mol/L. Conclusion: In this work, a highly efficient sensor for determination of DA was prepared with good sensitivity by GR and great selectivity of high special recognization ability by molecular imprinting membrane. This proposed sensor was used to determine the dopamine in human urine successfully.


2019 ◽  
Vol 11 (30) ◽  
pp. 3866-3873 ◽  
Author(s):  
R. Karthikeyan ◽  
D. James Nelson ◽  
S. Abraham John

Selective and sensitive determination of one of the purine nucleotides, inosine (INO) using a low cost carbon dot (CD) modified glassy carbon (GC) electrode in 0.2 M phosphate buffer solution (pH 7.2) was demonstrated in this paper.


Urban Climate ◽  
2021 ◽  
Vol 37 ◽  
pp. 100817
Author(s):  
Moritz Gubler ◽  
Andreas Christen ◽  
Jan Remund ◽  
Stefan Brönnimann
Keyword(s):  
Low Cost ◽  

2021 ◽  
pp. 1-9
Author(s):  
Javier Carrillo-Reche ◽  
Adrian C. Newton ◽  
Richard S. Quilliam

Abstract A low-cost technique named ‘on-farm’ seed priming is increasingly being recognized as an effective approach to maximize crop establishment. It consists of anaerobically soaking seeds in water before sowing resulting in rapid and uniform germination, and enhanced seedling vigour. The extent of these benefits depends on the soaking time. The current determination of optimal soaking time by germination assays and mini-plot trials is resource-intensive, as it is species/genotype-specific. This study aimed to determine the potential of the seed respiration rate (an indicator of metabolic activity) and seed morphological changes during barley priming as predictors of the priming benefits and, thus, facilitate the determination of optimal soaking times. A series of germination tests revealed that the germination rate is mostly attributable to the rapid hydration of embryo tissues, as the highest gains in the germination rate occurred before the resumption of respiration. Germination uniformity, however, was not significantly improved until seeds were primed for at least 8 h, that is, after a first respiration burst was initiated. The maximum seedling vigour was attained when the priming was stopped just before the beginning of the differentiation of embryonic axes (20 h) after which vigour began to decrease (‘over-priming’). The onset of embryonic axis elongation was preceded by a second respiration burst, which can be used as a marker for priming optimization. Thus, monitoring of seed respiration provides a rapid and inexpensive alternative to the current practice. The method could be carried out by agricultural institutions to provide recommended optimal soaking times for the common barley varieties within a specific region.


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